|Logically you will use another computer (not the one that is in trouble) to make the CD Johnw is suggesting.|
The boot disk Johnw is suggesting will not load onto the hard drive, or actually affect your personal files when you boot that problem computer with the CD.
Harking back to my earlier reply #3...
As you are naturally concerned about your personal files... perhaps take the time etc. to recover/safeguard them first?
Go to ubuntu.com and download the 'free" ISO for ubuntu, which save to a hard drive; then burn it to a DVD. Boot with that DVD. It will load itself (a Linux variant) into RAM only; it will not touch the hard drive itself.
Once it has installed itself and booted into a windows style desktop, you can locate the hard drive. Having done that you can (hopefully) simply copy all your files to DVD. Check the copies are OK on a least one other working system (if possible).
Then you can set about recovering a working system, safe in the knowledge that your files are safeguarded elsewhere; just in-case there is a risk to them...
And again as earlier advised, develop the habit of regularly copying/duplicating all your personal files to external storage. That way in event of similar nasty attacks... your files are safe elsewhere.
Incidentally MS never contact anyone personally - unless you request their assistance first. Even then there are checks that are required to ensure both sides of the discussion are legit...; MS will not ask for login/password details.